This application claims the priority of German Patent Document No. 101 35 587.4, filed 20 Jul. 2001, and PCT/DE02/02670, filed 22 Jul. 2002 the disclosure of which is expressly incorporated by reference herein, respectively.
The invention relates to an erosion system having an erosion head for removing metallic connection elements.
Up to now, core hole drills, which centrically cut away the connection element, for example, the rivet, have been used for removing connection elements. This drilling method has the disadvantage that structural parts, which are held together by the connection elements, may be damaged. This applies particularly to the removal of rivets because the latter have to be drilled out to the transition point situated between the rivet head and the rivet neck and this is the point of contact of the structural parts connected by means of the rivet.
Furthermore, in the airplane construction field, coupling rivets with high-strength drawing mandrels are used at points which are accessible only on one side. As a result, a very hard material is present specifically in the center of the rivet, whereby the following additional problems occur: The quality of the centering, that is, the precision with which the drill is applied, depends on the craftsman's manual skill, which, however, results in a scatter with relatively inexact centerings. In addition, the tool, that is, the drill, wears away particularly intensively on drawing rivets as a function of the exercised contact pressure. Another disadvantage is a possible development of heat which arises particularly when the cutting effect of the drill is considerably reduced because of wear or the rivet rotates along with the tool, whereby increased frictional heat is generated and may result in damage to the structure (structural change).
For these reasons, this drilling method has a limited suitability also for the removable of coupling rivets with drawing mandrels.
Apart from the above-mentioned technical problems, this drilling method results in very high physical stress to the implementing craftsman, which additionally impairs the quality of the process.
It is an object of the invention to provide a drilling method as well as a system for implementing the method by means of which a removal of connection elements from structural parts can be achieved which is as economical as possible, and the structural parts remain undamaged in a manner which is as reliable as possible.
This object is achieved by means of the characteristics of, a rotational drive (10) by means of which a tool is caused to rotate, a positioning system for moving the tool as well as a process control for controlling the overall system, the system comprising an energy unit and an electric circuit and, furthermore, the tool being a tube electrode through whose interior a dielectric can be guided to the surface of the connection element to be detached, the surface facing an interior portion, in order to cause a voltage between the tube electrode and the connection element to be detached, for implementing a spark erosion, characterized in that the rotational drive for the rotation of the tube electrode is arranged in a linearly movable application carriage and a positioning sensor system is provided on the drill head for determining the position of the drill head relative to the connection element, in that at least one video camera is provided which has a pertaining monitor unit with an image processing unit, for positioning the drill head and for controlling the chemical-mechanical erosion process, in that the process control has a laser spacing sensor in connection with an erosion control unit for controlling the position of the drill head relative to the connector surface (S) by way of the position of the application carriage as well as for controlling the signals transmitted to the energy unit, for determining the pulse durations, the average amplitude levels and amplitude maxima as well as the pulse separations of the erosion current.
It is an advantage of the system according to the invention and of the method according to the invention respectively that the process times as well as the tool wear can be reduced. Furthermore, the system according to the invention and the method according to the invention respectively permit an ergonomically advantageous operating sequence without any unusual physical stress to the implementing craftsman.
The invention will be described by means of the attached figures.